Larval development of the New Zealand geoduck Panopea zelandica (Bivalvia: Hiatellidae)

Abstract

The larval development of the New Zealand geoduck, Panopea zelandica, grown under culture conditions, was described through measurements of shell morphometry using video image analysis, photomicrographs, and scanning electron microscopy (SEM). Gametes were stripped from ripe broodstock and eggs fertilised with a dilute sperm solution. Developing larvae were maintained at 17 ± 1°C. Fertilised eggs developed into trochophores within 12 h and to D-stage larvae (105.3 μm shell length) within 24 h. Larvae spontaneously settled after c. 16 days at c. 247 μm shell length. Measurements of shell morphology, including total length, total height, hinge length, length of anterior end, and umbo length and height were adequate descriptors of larval development. SEM indicated that the provinculum of D-stage and developing veliger larvae lacked any teeth, although there was some development of a small lamelliform tooth on the hinge structure of newly settled post-larvae. Prominent spines common on dissoconch shells of other hiatellid clams were absent in newly settled post-larvae of P. zelandica. The data presented here are the first description of the larval development and larval biology of P. zelandica. The relative ease of spawning and rearing of P. zelandica suggests that the development of commercial hatchery technology for this species warrants further investigation. © 2003, Copyright Taylor & Francis Group, LLC.